Automatic load-regulating transmission mechanism



Dec. 7 1926. LGWABQ L. B. STRONG AUTOMATIC LOAD REGULATING TRANSMISSION MECHANISM Filed Sept.- 1922 3 Sheets-Sheet 1 Fig.1

Dec. 7', 1926.

B.- STRONG v AUTOMATIC LOAD REGULATING TRANSMISSION MECHANISM Filed Sept. 1, 1922 3 Sheets-Sheet INVENTOR.

" ATTORNEY.

Dec. 7 1926.

. L. B. STRONG AUTOMATIC LOAD REGULATING TRANSMISSION MECHANISM I k \i K W% v -2 a' & 6

' %izw w INVENTOR.

Patented Dec. 7, 1926.

LEON 2B. STRONG, or DENVER, COLORADO.

AUToMATIc LOAD-BEGULATING TRANSMISSION Manama,

Application filed September 1, 1922. Serial no. 585,688 r This invention relates to a transmission mechanism and has for aprimary object to provide a mechanism, the parts ofwhibh are so constructed and arranged that a v change in the resistance imposed upon a driven machine automatically produces a change in mechanical advantage such that the load upon the prime mover will not be materially affected thereby. A. further object of the invention is to provide an integral frame, in a device ofthis character, so

arranged that the bearings therein will be held in alignment and in proper relation to each other. 1

With this object in view, the invention will be better understood from the following detailed description taken in connection with the accompanying drawings, wherein: :Figure -1 is a top plan view of the mecha msm; a Figures 2 and 3, the construction of the curve constituting the generatr'ix 'of cone 11;

Figure 4 is a section on the line A-A. 'Again referring to the drawing illustrating one manner in which the invention may be constructed, the numeral 10 designates a drive shaft, mounted for longitudinal as well as rotary motion inbearings 1 and 2,

.30 having one end fitted with a cone 11 and variably forced toward the driven shaft 12 by a spring 13, having one end secured to a lug 14 of main casting 9 and its free end forcing said drive shaft in. said mentioned direction through end thrust bearing 15.

' Bearings 1, 2, 3 and 4 are pivotallymount-.

ed between forked projections 5, 6, 7 and 8. respectively, to insure even distribution of working 'pressure on said bearings.

Arranged in engagement with a point on the surface of the cone 11 is a circular ring 16 whose cross-section is substantially a right, angle subtended by a circular are, said circular are forming the exterior portion of said ring. Thus, it will be seen, that as a point only of the surface of the cone is engaged at any one time, the tendency to excessive wear and loss of power is eliminated by causing a rolling driveefi'ect.

1 Pivotally arranged between forked projection 5 of casting 9 is a housing 4, rotatably holding sleeve 16 in one position relative to the stationary members by radial roller bearing 17 and end thrustbearing. 18.

Mounted upon sleeve 16 is a pulley 20 conmeeting the driven machine with driven shaft 12 by means of a belt carried thereon and spiral thread 19.

It should now be clear to one skilled. in

the art, that with shaft 12 turning in the di-o 60 rection indicated by the arrow, same will be forced to the right in direct proportion to torsion load on driven pulley 20. It should also beclear that the end thrust thus generated will be transmitted from bearing 18 to spring-13, through longitudinally adjustable shaft 12, ring 16, cone 11, shaft 10 and bearing 15 and that said spring will be deflected proportionately to the component of force in the direction of its length, thereby automatically varying the effective radius of the cone.

Figure 4 is designed to show, in a general way, the interior construction of radial bearings 1, 2 and 3, also to show more clearly the construction of ring 16 and the-means for holding same concentric with, and in one position'rela'tive to driven shaft 12.

' Surrounding shaft 12 is a hollow cylinder 21, pivotally mounted between forked project-ion 6 of main casting 9. -Arran'ged between shaft 12 and the internal cylinder surface of cylinder 21 are steel balls 22' of such a size as to hold shaft 12 concentric with cylinder 21. Loosely -mounted upon shaft 12 are flanged cylinders-23, 24 and 25, so positioned as to yieldably hold the balls in a predetermined position by means of springs 26-and 27. Thus it will be seen that, as longitudinal movement of shaft 12 takes place, the balls roll rather than slip in accordance with this. movement, and are gently forced back to a vpredetermined position when longitudinal movement of shaft .12- c eases.

Pivot 28 is so positioned that when the'load upon shaft 12 reaches a maximum, the clockwise and counterclockwise moments of force acting on shaft 12 about that pivot balance, therebv relieving the spi rally threaded portion of shaft 2 of radial strain, Let us now consider the derivation of a formula whereby we can determine the amount of the torsion load P in pound feet upon shaft 1 in terms of known (11181111111165.

T the-thrust of spring 13 in pounds,

S the effective radius of cone 11 in inches,

9 the angle between a line tangent to the curved contour of the cone at the point of contactand a line perpendicular to the axis of the cone, I; the efiective radius of ring 16 incinches, an r L the lead of spiral thread 19 in inches per revolution.

1 Let F equal force acting tangentially to ring 16 and cone 11.

Since thrust upon shaft 12 toward the right due to torque on the feed. screw is,

- 21rRF I and, equal and opposite thrust due tothe atrix of cone 11 must be such that the result obtained by use ofthis equation is the same, regardless of the point of enligagement.

Assuming the curve BC, ig. 2, to be so roportioned that for any line, as the line FE, drawn tangent to the curve at any point upon it, as'the point a, the product TS tan 8 1s constant, then the spring thrust component in a direction perpendicular to the axis of the cone will vary in inverse proportion to S, and the mechanical work done in moving the driven shaft longitud-v inally, like the work of isothermal compression of a gas, will be proportional to log. P /P,; where P is the initial pressure and P the final pressure, for the variation in pressure is then identical.

Defining a as the distance from the X axis at which work of deflection vof the spring is begun, and placing P equal to unity at this distance, the expression log. P /P may also be written simply log. P

P at any lesser distance Y or S' becomes a/y and the expression log. P becomes log. a/y or log. wlog. y, and the mechanical work done in moving the driven shaft a distance a-y and stored in the spring as 'otential energy is then proportional to. og. a-log. :1

Since the thrust of a spring is proportional to its deflection it follows that its stored potential {energy varies directly as the square of its deflection, .and that an amount of work roportional to log. a-log. 3} expended in efiecting said springwill equation of the required curve namely Obviously, the curve formingthe generproduce a deflectionproportional to We then have the sought for defining X C /log, a-log. y.

' It is not found practical", however, to make the cross sectional radius of ring 16 suificiently small that the variation of the effective radius of said ring may be neglected, for this external radius must be sufii ciently large that the material of which the ring is made will not be permanently depressed by the t-ractive force. This variation of the effective radius of the ring can be practically compensated for as follows:

As in Figure 3, plot points F, a, a, a", a' 'C. Taking a radius equal to the external radius of ring 16 and with centers upon and draw the curve F C tangent to these arcs. From C, the oint of tangency between the curve F with the arc whose center is' at C, lay off C'D arallel and equal to CD. Draw ED' an let this be the new axis of the cone. Since F C is, by construction, parallel to FC, it should be clear that for any given position of ring 16 withrespect to the axis ED the angle 8 and the spring deflection will not be afl'ect- 'ed by the considerable external radius of ring 16. Since, by construction, C'D is equal to CD, the effective radius of the cone at this point will be the same as in Figure 2, but, as the spring 13 contracts with a decreased stress due to a lightened load upon pulley 20, this efiective radius will increase the points plotted, strike oif arcs as shown,

more rapidly than with the construction of Figure 2; If the maximum and minimum mechanical advantage is now determined, an amount to add to the sprin deflection can be found by a simple ca culation that will make the torsion load upon shaft 1 with engagement at F equal to the load with engagement at C. It] will then be found that for intermediate points, the torsion load upon shaft 1 will not vary greatly. .t

.It.i s of course to be understood that'the parts of the invention may be constructed in other manners and associated in other relations, therefore, I do not wish to be limited in any manner except as set forth in the claims hereunto appended.

What I claim is:

1. A transmision mechanism of the class described comprising a cone and a disc, said disc contacting at its periphery with said ,cone, said cone having the contour defined by the equation x= cJlog. alog. y

and an axis of rotation arallel to the axis 0:. -2.. A bone fOI' tIQIISmISSIOD mechamsms of the class described having a generatrix based on the formula 'x= c /log. alog. y and an axis of rotatiOn parallel to the w axis. 3. The combination in a transmission mechanism comprising a driving shaft and adriven shaft mounted at an angle to'each other and both movable longitudinally; load actuated means for moving said shafts longitudinally, a disc actuated-.by one of said shafts, said disk carrying a detachable peripheral ring, and a cone carri'edby the other of said shafts and having its surface, in contact with saidring, said cone having a contour defined by the equation X= c /log. al0g. 'y and an axis of rotation parallel to the :1: axis.

4. The combination in a transmission mechanism comprising a drive shaftand a driven shaft mounted at an angle to eachflother, said sh'afts being simultaneously mov'able'longitudinally; loadactuated means for moving said shaft longitudinally; a disk carried by one of said shafts; a cone contacting with said disc and carried by the other of said shafts and bearings for said shafts, of an integral frame supporting all of said bearings, each of said bearings being pivoted in said frame for revolution in the same plane with each other. 4

5; A transmission mechanism of the class described comprising a cone and a wheel, said Wheel contacting at its periphery with said cone, in which the contacting surface of the cone has a contour parallel to the curve defined by the equation ax= (x /log. alog.

cone to the curve defined bythe equation- 6. A cone for transmission mechanism of the class described, the contour of the contacting surface of which is parallel to the curve defined by the equation and an axis of rotation parallel to the an axis. g

7 The combination in a transmission mechanism, comprising a driving and a driven shaft inounted'at an angle to each other and both movable longitudinally; load actuated means for moving said shafts longitudinally, a ring concentric with and fixed in one position relative to said driven shaft, said ring being separable from its support and'a cone carried by the other of said shafts and having its surface in contact with saidring, said having its contacting contour parallel x= m/log. a-log. y Y

and an axis of rotation parallel to the axis. I

8. The combination, in a transmission mechanism, of a drive shaft; a driven shaft mounted at an angle thereto, said shafts being simultaneously movable; load actuated means for moving said shafts longitudi- 1 a ring fixed in one position relative nally; to, and concentric with, one of said shafts;

a cone contacting with said ring and car-i ried on the other of said shafts; bearings for both said shafts and an integral frame sup-' porting all of said bearings, each of said bearings being pivoted for revolution in the same plane with each other. v

In testimony whereof I have allixed my signature.

LEON B, STRONG. 

